Understanding and control of the episodic pain and health care use among adults with sickle cell disease. Information gathered from this project will help to develop programs that will help patients , their physicians, nurses, and other health care providers better control the pain that is associated with sickle cell disease. During the term of the project, two blood samples will be drawn, one at the beginning, and one at the end of the study. The samples will be small and will be used to determine what type of sickle cell disease is present and to examine blood factors that may be associated with pain. On the first meeting, several questionnaires will be filled out. These questionnaires will give information about the subject's general health, concerns about how this disease effects his/her life, how pain is dealt with, if others are relied upon for suport, interactions with others, and emotions during the past week. At the first meeting, the subject will be shown how to keep a pain diary. Twelve two-week diaries will be kept during the project. The diary will indicate the rate of pain, medication taken, visits to the physician, or hospital/clinic visits due to pain. Insertions into the diary will take only minutes per day. Each two-week diary will be mailed to the investigators and a new diary, along with some compensation, will be sent back to the patient. At completion of the twelve diaries, there will be a final session at the sickle cell clinic, at which time, another blood sample will be drawn. A last questionnaire about the patient's general health will be filled out at this time.